Types of SQL Statements

The lists in the following sections provide a functional summary of SQL statements and are divided into these categories:

Data Definition Language (DDL) Statements
Data Manipulation Language (DML) Statements
Transaction Control Statements
Session Control Statements
System Control Statement
Embedded SQL Statements

Data Definition Language (DDL) Statements

Data definition language (DDL) statements let you to perform these tasks:

Create, alter, and drop schema objects
Grant and revoke privileges and roles
Analyze information on a table, index, or cluster
Establish auditing options
Add comments to the data dictionary

The CREATE, ALTER, and DROP commands require exclusive access to the specified object. For example, an ALTER TABLE statement fails if another user has an open transaction on the specified table.

The GRANT, REVOKE, ANALYZE, AUDIT, and COMMENT commands do not require exclusive access to the specified object. For example, you can analyze a table while other users are updating the table.

Oracle Database implicitly commits the current transaction before and after every DDL statement.

Many DDL statements may cause Oracle Database to recompile or reauthorize schema objects. For information on how Oracle Database recompiles and reauthorizes schema objects and the circumstances under which a DDL statement would cause this, see Oracle Database Concepts.

DDL statements are supported by PL/SQL with the use of the DBMS_SQL package.

Data Manipulation Language (DML) Statements

Data manipulation language (DML) statements access and manipulate data in existing schema objects. These statements do not implicitly commit the current transaction. The data manipulation language statements are:

CALL
DELETE
EXPLAIN PLAN
INSERT
LOCK TABLE
MERGE
SELECT
UPDATE

The SELECT statement is a limited form of DML statement in that it can only access data in the database. It cannot manipulate data in the database, although it can operate on the accessed data before returning the results of the query.

The CALL and EXPLAIN PLAN statements are supported in PL/SQL only when executed dynamically. All other DML statements are fully supported in PL/SQL.

Transaction Control Statements

Transaction control statements manage changes made by DML statements. The transaction control statements are:

COMMIT
ROLLBACK
SAVEPOINT
SET TRANSACTION

All transaction control statements, except certain forms of the COMMIT and ROLLBACK commands, are supported in PL/SQL. For information on the restrictions, see COMMIT and ROLLBACK.

Session Control Statements

Session control statements dynamically manage the properties of a user session. These statements do not implicitly commit the current transaction.

PL/SQL does not support session control statements. The session control statements are:

ALTER SESSION
SET ROLE

System Control Statement

The single system control statement, ALTER SYSTEM, dynamically manages the properties of an Oracle Database instance. This statement does not implicitly commit the current transaction and is not supported in PL/SQL.

Embedded SQL Statements

Embedded SQL statements place DDL, DML, and transaction control statements within a procedural language program. Embedded SQL is supported by the Oracle precompilers and is documented in the following books: